He is also a suspect in at least five other child murders, including the abduction of the Beaumont children from Glenelg Beach in South Australia and the murder of 3-year-old Simon Brook from New South Wales.

Other witnesses include criminologists and police who have analysed all of the cases he is a suspect in.

The coroner has questioned the reliability of any evidence he may give.

Percy's lawyer suggested psychologist Dr James Ogloff should be the first witness in the inquest, as he had the most involvement with Derek Percy.

He argued after Dr Ogloff's evidence the coroner may be in a better position to determine whether Percy should be compelled to give evidence.

A date for the inquest is yet to be set but is expected to run for up to 5 days.